HAL Id: jpa-00218647
https://hal.archives-ouvertes.fr/jpa-00218647
Submitted on 1 Jan 1979
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
TEMPERATURE DEPENDENCE OF MAGNETIC ANISOTROPY IN AMORPHOUS Fe-B ALLOYS
H. Onodera, H. Yamamoto, H. Watanabe
To cite this version:
H. Onodera, H. Yamamoto, H. Watanabe. TEMPERATURE DEPENDENCE OF MAGNETIC
ANISOTROPY IN AMORPHOUS Fe-B ALLOYS. Journal de Physique Colloques, 1979, 40 (C2),
pp.C2-142-C2-143. �10.1051/jphyscol:1979249�. �jpa-00218647�
JOURNAL DE PHYSIQUE Colloqete
C2,
suppl6ment au no 3, Tome 40, mars 1979, page C2-142TZMPERATURE DE?ENDENCE OF M A G N E T I C ANISOTROQY I N AMORPHOUS Fe-B ALLOYS
H. Onodera, H. Yamamoto and H. Watanabe
The Research I n s t i t u t e for Iron, S t e e l and Other Metals, Tohoku Univ., Sendai, Japan
Rdsum6.- L'influence de la tempgrature et de la composition sur la distribution de champ hyperfin magndtique dans les alliages amorphes Feloo-xBx (14 <x<21) a dtd dtudide par spectromdtrie Mgssbauer.
L'axe d'aimantation facile est, dans le plan du ruban 1 la ternpgrature ambiante, mais s'dloigne de ce plan 5 partir de 160 K. A basse tempsrature, le pic de distribution de la courbe de champ hyperfin prdsente une structure correspondant 1 des domaines dont la direction d'aimantation depend fortement de la tempdrature.
Abstract.- The temperature dependence of the magnetic anisotropy and the composition dependence of the distribution of the magnetic hyperfine fields in amorphous Feloo-gBx (x = 14 -21) alloys have been studied by the Mijssbauer effect measurements. Easy axis of magnetizat~on at room temperature is in the plane of the ribbon, while it tilts out of the plane below 160 K. At low temperatures the peak in the distribution of hyperfine field curve, as deduced from the middle line intensity, PP, has a struc ture which shows the presence of domains whose magnetization direction is strongly temperature depen- dent.
1. Introduction.- Since ~zssbauer spectroscopy is useful for studying the microscopic state in magne- tic materials, many ferromagnetic amorphous alloys have been studied by 5 7 ~ e Mzssbauer effect. Most of the studies are concerned with the distribution of hyperfine fields, and the patterns of the magnetic hyperfine field distribution obtained by computer analysis are not much different from those of crys- talline disordered alloys. Chien and Hasegawa obser- ved that the magnetization direction of an amorphous Fe4,Ni4,P1,Bs sample lies in the plane of the ribbon above 240 K, and tilts out of the plane continuously with temperatures below 240 K /I/. Below 110 K, how- ever, the magnetization direction begins to tiltback toward the ribbon plane. Similar behaviors were also observed in FeeoPI6BlC3, Fe,9Ni4,P14B6Si, /I/, Fe80B20 and Fe75P10C15 /2/. Since the observations of the magnetic domain structure have shown that there exist two different types of domain i.e. a maze domain and a 180' domain at room temperature 131, 141, one may postulate another mechanism where the total volume of domains with the magnetization di- rection parallel to the ribbon plane decreases through the domain wall motions and those with the magnetization direction perpendicular to the plane increases, instead of the tilting motion.
The magnetic anisotropy in amorphous Fe-B, Fe-P systems and in FesoP17Cs has been studied by torque measurements by Takahashi et al. and tilting 2f the magnetization out of the ribbon plane at low temperatures has been established /5/. The magnetic anisotropy in these amorphous alloys has been consi-
dered to be induced by stresses 141, /6/, 171 and the direction change of the magnetization axis with temperature has been considered to be caused by the thermal variation of the stresses
111.
In the pre- sent study we report the temperature dependences of the magnetic anisotropy and the composition depen- dence of the distribution of the magnetic hyperfine fields in amorphous Feloo-,Bx (x=14%21) alloys.2. Experiments 'and Results.- The amorphous Fe-B sam- ples were prepared by rapid quenching from the molten alloys using the single roller type quenching appa- ratus. The ribbons thus obtained are 1-2.5 mm in width and 20-60 um in thickness. The amorphous state
of samples were confirmed by the X-ray diffractions.
The measurements of the Mzssbauer effect have been performed with a conventional method in which the direction of y-rays from the Pd ("co) source is perpendicular to the ribbon plane. Figure 1 shows the temperature dependence of the intensity of the middle absorption lines, which are caused by the
I I
transitions between
+-
and ty levels. The intensity 2scale is chosen so that the intensity of the outer- 3 1
most lines (+F
-
+?) is set equal to 3. With this scale, the intensity 4 corresponds to the magneti- zation direction being parallel to the ribbon plane, while 2 corresponds to a random distribution of the magnetization direction. Similar temperature depen- dence of the middle absorption lines has been repor- ted /I/, /2/ as stated in the introduction. As can been seen from the figure the intensities of the middle lines are less than 4 at room temperature, and the increase of the intensity is not always ob-Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979249
served below 110 K f o r a l l t h e samples. The Mgss- P1,3 and Pz a r e shown i n f i g u r e 2 where both d i s t r i - bauer s p e c t r a have been analyzed w i t h t h e computer b u t i o n c u r v e s a r e normalized by *P(H)~H=I i n or- by a modified ~ e s s e - R i i b a r t s c h ' s method / 8 / i n which d e r t o make comparison e a s i e r .
t h e d i s t r i b u t i o n of h y p e r f i n e f i e l d s appeared i n 3 . g i s c u s s i 0 n . - The i n t e n s i t y r a t i o of t h e s i x l i n e s
3 1
-
1(*7
-
k7) and (ti-
+ a b s o r p t i o n l i n e s (Pi ,3) and i n t h e S 7 ~ e Mgssbauer spectrum i s g i v e n by1 1
t h a t i n t h e (k7
-
k T ) l i n e s (P2) can be o b t a i n e d 3:f ( 8 ) : 1: 1: f ( 8 ) : 3 where f (8) = 4 s i n 2 8 / ( l + c o s 2 8 ) and s e p a r a t e l y . 8 i s t h e a n g l e between t h e d i r e c t i o n s of y-rays and of t h e h y p e r f i n e f i e l d a t 5 7 ~ e n u c l e i . Hence t h e in- f o r m a t i o n emphasized about t h e h y p e r f i n e f i e l d s ' 1 n e a r l y p a r a l l e l t o t h e r i b b o n p l a n e i s included i n P z . P2 o b t a i n e d from t h e s p e c t r a a t room temperature where the m a g n e t i z a t i o n d i r e c t i o n s a r e n e a r l y p a r a l - l e l t o t h e p l a n e h a s a s i m i l a r shape t o t h a t of P1,3 However, t h e shapes of Pz a r e d i f f e r e n t from t h o s e of PI,^ a t 20 K a s shown i n f i g u r e 2, having a c e r - t a i n s t r u c t u r e i n t h e l i n e p r o f i l e . The shape of P2 a r e depressed roughly i n t h e middle p o s i t i o n of t h e peak a s compared w i t h t h o s e of PI,^. This would mean t h a t 5 7 ~ e atoms which have t h e h y p e r f i n e f i e l d s clo- s e t o t h e mean v a l u e have t h e i r s p i n d i r e c t i o n much1
I, , ,
I, , I I I I I
t i l t e d away from t h e r i b b o n p l a n e . I f we simply
0
0 100 2 00 3 0 0 assume t h a t t h e w i d t h of t h e peak i n P(H) curve comes Temperature ( K from t h e compositional f l u c t u a t i o n , t h e above r e s u l t F i g . 1 : Temperature dependences of t h e i n t e n s i t y of may be stated as the substance is made up of
t h e middle peaks. The broken l i n e corresponds t o t h e t y p e s of domains, one having t h e B c o n t e n t c l o s e t o c a s e of random d i s t r i b u t i o n of m a g n e t i z a t i o n d i r e c -
t i o n s . t h e nominal composition and t h e s p i n d i r e c t i o n s til-
t e d o u t of t h e r i b b o n p l a n e , w h i l e t h e o t h e r having t h e B c o n t e n t d e v i a t e d from t h e nominal composition and t h e s p i n d i r e c t i o n s i n t h e r i b b o n p l a n e . The mechanism l e a d i n g t o t h i s r e s u l t i s considered t o be
t h e i n t e r n a l s t r e s s caused by t h e f l u c t u a t i o n i n t h e composition.
References
/ I / Chien, C.L. and Hasegawa, R., J . Appl. Phys.
2
(1976) 2234.
/2/ ~ a k A c s , L., S o l i d S t a t e Commun.
21
(1977) 611./ 3 / Kronmuller, H., S c h a f e r , R., and Schroeder, G . , J . Magnet and Magnetic Mater.
5
(1977) 61./ 4 / Becker, J . J . , AIP Conf. Proc.
2
(1976) 204.151 Takahashi, M., Ono, F. and Takakura, K., Japan J . Appl. Phys.
2
(1976) 183. Takahashi, M., Ikeda, N. and Miyazaki, T., Japan J . Appl. Phys.15 (1976) 1821. Takahashi,iM. and I s h i o , S.,
-
Japan J . Appl. Phys.2
(1977) 2273.161 S h i l l i n g , J.W., AIP Conf. Proc.
9
(1976) 220.Hyperfine Field ( k Oe /7/ Egami, T . , F l a n d e r s , P.J. and Graham, G.D., Appl.
Phys. L e t t .
26
(1975) 128; AIP Conf. Proc.26
F i g . 2 : The d i s t r i b u t i o n s of magnetic h y p e r f i n e (1975) 697.
f i e l d s a t 20 K. The s o l i d l i n e s and t h e broken l i n e s 181 Hesse, J. and Riibartsch, A., J . Phys. E, z ( 1 9 7 4 ) correspond t o P1,3 and P2, r e s p e c t i v e l y . 526. The modified method w i l l be published e l s e -
where by t h e a u t h o r s .
